I have had my Marlin XL7 for around three years and even killed my first deer with it at 235 yards. It was an out of the box awesome shooter with cheap Federal blue box... But this past year I noticed the groups had opened up to around 1- 1/2" at 100 yards.
I didn't mess with it much since I didn't even get a chance to take her in the woods since I became a new father right before season opened up. I won a case of Nosler Trophy Grade ammo during the Outdoor Channel Oct. sweepstakes (awesome) and it came in the other day.
I went ahead and got my rifle out, cleaned her up good and took a good look at the bore. To my surprise I had copper fouling. I then read my jar of solvent only to find that it didn't do copper. After a lot of work with Hoppe's #9 and some foaming copper eating stuff, I got a clean patch out.
Took her out today to test the Nosler ammo. Before shooting fatigue set in, I was able to get a 4 shot group that measured .725" from center to center! What more can I ask of a gun I paid a whopping $330 for!
I topped mine off with a Nikon Monarch 5-20X44 with BDC recticule. I LOVE tis scope. Very clear through all the zoom levels. I shot my deer on around 12-14 power if memory serves me right. Haven't killed another one with it yet. Got one with my muzzle loader the next yer and only bow hunted this past year.